Division Rhodophyta
Red Algae
I. Characteristics
A. Usually multicellular with branched thallus
B. Often sexual with male and female gametes - usually non-motile
C. Cell wall with cellulose & pectic compounds.
D. Chloroplasts with chlorophylls a & d, carotenes, xanthophylls,
& usually phycoerythrins & phycocyanin
E. Food reserves - floridean starch & floridoside
II. Distribution
Mainly marine, commonest in warm oceans. Usually attached. Occur at
greater depth than any other photosynthetic organism - 200 m+
III. Life cycle - very complex, with whole new set of terminologies.
IV. Representative genera.
A. Porphyra
Common on rocks in intertidal zones of N. Am. Thallus
is flat to convoluted sheet, attached by holdfast.
B. Nemalion
Common on rocks in middle intertidal zone Composed
of wiry branching filaments.
C. Polysiphonia
Common genus of intertidal zone of N. Am. Reddish
or pinkish, delicate much branched thallus.
D. Coralline algae.
Corallina. Marine red algae with heavily
calcified thallus. Major contributors to formation of coral reefs. Closely
intermingled with coral animals.
E. Batrachospermum
V. Economic importance
A. Source of agar
1. culture medium for micro.
2. bulk producer in laxatives
3. stabilizer & filler for many foods
B. Source of Carrageenin (Chondrus crispus - "Irish moss")
1. Emulsifier & stabilizer - e.g.. in chocolate
milk
C. Food source
D. Reef formation
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